Lucky accidents of human evolution: Energy upgrade

By Clare Wilson

While it is tough to work out just how our brains got so big, one thing is certain&colon; all that thinking requires extra energy. The brain uses about 20 per cent of our energy at rest, compared with about 8 per cent for other primates. “It’s a very metabolically demanding tissue,” says Greg Wray, an evolutionary biologist at Duke University in Durham, North Carolina.

In the past year, three mutations have been discovered that may have helped meet that demand. One emerged with the publication of the gorilla genome, in March (Nature, vol 483, p 169). This revealed a DNA region that underwent accelerated evolution in an ancient primate ancestor, common to humans, chimps and gorillas, some time between 15 and 10 million years ago.

The region was within a gene called RNF213, the site of a mutation that causes Moyamoya disease – a condition that involves narrowing

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